Wednesday, July 19, 2023

Monarch Butterfly Update -- July, 2023

How many monarch butterflies are people seeing this year? I've seen a grand total of two thus far. Neither paused for a photograph, so this picture is from a past year. 

On July 11, I saw one flying crazily at the Barden. They are expert and often seemingly whimsical flyers, but this one's flight was unusually frenetic. At double the usual pace, it would approach flowers but not land on them, leading me to speculate that it was looking for a mate rather than nectar. A useful Q&A post at suggests that these episodes of particularly erratic flight are induced either by a predator's attack or by a male chasing a female. But the frenetic flight made me instead imagine what it is like for monarchs when their numbers are few, and the search for a mate consumes more and more of their energy. Might a fruitless search at some point become frantic?

A few days later, I saw a monarch in a pasture near Herrontown Woods, flying at a more measured pace. 

There were a few common milkweeds growing in the pasture, but I was particularly happy to discover a couple specimens of green comet milkweed (Asclepias viridiflora), growing there as well. It's a species I've only seen twice in Princeton, the other incidence being a few individuals in the Tusculum grasslands. 

It's common to think that monarchs gain all their sustenance from milkweeds, but in fact the adult butterflies obtain nectar from a broad range of flowers. Otherwise, they would starve after the milkweeds have finished blooming. The caterpillars, however, are highly particular, and will only eat the foliage of milkweeds. The milkweed foliage is around all season long for the munching, though a lot has to happen for the foliage to actually be put to use. A female needs to lay eggs, and those eggs need to elude predation long enough to hatch. I have not seen an actual caterpillar in years, nor much evidence of milkweeds being consumed, but clearly a few are surviving somewhere.

To get a more in-depth report on the status of monarchs, my go-to is the savant Chip Taylor, who blogs at MonarchWatch. In a June 14 post, writing about whether monarchs will be listed as threatened or endangered, Chip Taylor wrote openly about the eventual end of the great monarch butterfly migration. It's believed that the monarch itself is not likely to go extinct, but that the migration--involving the portion of monarchs that participate in the fantastic journey north from the mountains of Mexico up into the U.S. and Canada, then back to Canada in the fall--is increasingly vulnerable. According to Taylor,
"As applied in this case, extinction refers to the loss of the monarch migration and not the species per se. Given the link between the increase in greenhouse gas emissions and increasing temperatures and the world’s slow response to these changes, yes, the monarch migration will eventually be lost."

It's important to note that those who raise alarms about the climate crisis are the optimists. It is optimistic to face up to a grave risk, and call for action to save what will otherwise be lost. Denial and dismissiveness are rooted in pessimism. They take a gloomy view of 1) our capacity to recognize dangers and 2) our capacity to act collectively to prevent catastrophe. Taylor's recognition of the high likelihood that we will lose the migration raises an obvious question, which he hastens to answer.

"If the monarch migration will be lost eventually, why make great efforts to sustain it? Faith. We have to have faith that the world will come to its senses and work collaboratively toward the reduction of greenhouse gases to save the natural systems that sustain us. There is hope. The rate of increase in CO2ppm has declined in recent years."

Another answer is that, the longer the migration can be maintained, the longer humanity has to "come to its senses." 

It is stunning, knowing the extraordinary power of carbon dioxide to influence the earth's climate, that society has left it unregulated. As individuals, cities, and businesses, we remain free to pour as much of it as we please into the atmosphere. Until that giant hole in our regulatory protections is patched, the vast majority of people will not change their behavior. 

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